The investigator proposes to study the function and assembly of the dystrophin and utrophin associated protein (DAP/UAP) complexes in skeletal muscle. Regions of dystrophin required for formation of stable DAP/UAP complexes will be identified, DAP/UAP complexes will be identified, DAP/UAP complex associate cytoskeletal or membrane proteins will be isolated, a novel associated protein will be studied in detail. The investigator will employ transgenic and knock-out mouse technologies to analyze function of key protein, as well as immunological and biochemical fractionation together with yeast two-hybrid studies to identify and characterize interactions between associated proteins.